measurement of t-violating transverse muon polarization in k+ ：的t-violating的k +横介子极化测量

J-PARC E06 K+0+(K3)用時間反転非保存探索実験新型光活用法,Dec 8, 2006第2回次世代光関,清水俊大阪大学理学研究科,Transverse muon polarization,Spurious effects from final state interaction are small. Non-zero PT is a signature of T violation.Clear channel to search for T violation. Long history of theoretical and experimental studies. (J.J. Sakurai, 1957)Experiment at KEK(E246) PT = - 0.0017 0.0023(stat) 0.0011(syst) ( |PT | 0.0050 : 90% C.L. ) PRD73, 72005(2006),K+p0m+n decay,T-odd,Matrix element of K+p0m+n decay,PT is sensitive to scalar couplings.,T-violation parameter : Im(),Im()0 T-violation,Theoretical aspects,Standard Model contribution to PT : Only from vertex radiative corrections and PT(SM) 10-7Spurious effects from final state interactions (FSI): PT(FSI) 10-5There is a large window for new physics beyond the SM in the region of PT = 10-3 10-5There are theoretical models which allow sizeable PT without conflicting with other experimental constraints.,Multi-Higgs doublet (3 Higgs doublet) model (MH)SUSY with s-quark mixing (SUS)SUSY with R-parity violation (SUR),KEK 全体図,KEK-12GeV PS,Stopped K+ methodLarge solid angle and high resolution of Toroidal Spectrometer and CsI(Tl) calorimeter,side view,end view,decay,T-violation search in KEK E246 experiment,Experimental setup,Double ratio measurement PT(0 forward) PT(0 backward) PN contribution to systematic error is drastically reduced.,Determination of PT,Stopped K+ beam,Stopped K+ target、fwd/bwd 0検出器重要鍵。,K+静止用,K+静止崩壊用直径8cm6本構成読出：PMT（浜松H1635)K+ 崩壊位置特定,P 測定,measurement of P, P,S,P：CsI(Tl) calorimeter,Using Stopped K+,not only 2 but also 1 with high energy,MeV,CsI(Tl) photon detector,Segmentation Dq= Df= 7.5oNumber of crystals 768Length of crystals 25 cm (13.5 X0)Inner radius 20 cmOuter radius 50 cmSolid angle 75%of 4p Readout PIN diodeLight yield 11000 p.e./MeVEquiv. noise level 65 keVE/E 12-14% at 1257 keV(22Na)E3% at 200MeV,D.V.Dementyev et al. Nucl. Instr. Method A440 (2000) 151,Pin diode使用、強磁場利用可能省化,E246 result,PT = - 0.0017 0.0023(stat) 0.0011(syst) ( |PT | 0.0050 : 90% C.L. )Imx = - 0.0053 0.0071(stat) 0.0036(syst) ( |Imx | 0.016 : 90% C.L. ),Statistical error dominant,AT = (Afwd - Abwd ) / 2 Ncw - NccwAfwd(bwd) = Ncw - NccwPT = AT / a a : analyzing power : attenuation factor Imx = PT / KF KF : kinematic factor,New experiment at J-PARC,We aim at a sensitivity of dPT 10-4 (E246-dPT 10-3)Statistical errordPTstat 0.1 dPTstat (E246) 10-4 with 1) 30 of beam intensity, 2) 10 of detector acceptance, andhigher analyzing powerSystematic errordPTsyst 0.1 dPTsyst (E246) 10-4 by 1) precise calibration of misalignments using data 2) correction of systematic effects,JPARC,J-PARC 施設,Parameters of Main Ring Extraction Beam Energy50 GeVAverage Beam Current15 ARepetition0.3 HzExtraction SchemeFast, and Slow,Method of experiment,Stopped K+ decaySuperior to in-flight decayToroidal spectrometer,E246 detector upgradeWell known performanceWell studied systematicsGood alignment in magnet and CsI(Tl)Lower cost,FoM (AN) distribution,Detector acceptance,Upgrade of the detector,Muon polarimeter passive activeMuon magnetic field toroid muon field magnetTarget smaller and finer segmentationCharged particle tracking addition of two chambersCsI(Tl) readout PIN diode APDNew analysis scheme,Target,Smaller size (smaller beam spot) Finer segmentation Sci. fiber of 20 cm length Clear fiber or direct attachment Light readout by SiPMTs,Diameter 6 cmActive length 20 cmFiber size 2.52.5 mmNo. of fibers 432Light readout 4 clear fibersLight yield 10/SiPMT,Target and tracking,Better kinematical resolutionStronger Kp2 dif m+ BG suppression,Addition of C0 and C1 GEM chambers with - high position resolution - higher rate performance,Larger C3-C4 distance Use of He bags,New target,E246,J-PARC,CsI(Tl) readout,CsI(Tl) + APD + Amplifier + FADC Electrons after APD : 2 107 100 MeV Max count rate / module : 100 kHz Max K+ decay rate : 20 MHz - enough for the beam intensity in Phase 1 Noise level : to be tested Module energy resolution : to be testedEnergy resolution is determined by lateral shower leakage,Sensitivity estimate,Source dPT Net run time 1.0 107 sProton beam intensity 9mA on T1K+ beam intensity 3106 /sTotal number of good Km3 2.4109Total number of fwd/bwd (N) 7.2108Sensitivity coefficient 3.73NTotal 10-4,Statistical sensitivity,Systematic errors,Source dPT dz 10-4 qz 10-4 qe+, Ee+ 10-4,Total 10-4,JPARC,Summary,PT in Km3 is a very sensitive probe of new physicsWe propose a J-PARC experiment in the early stage of Phase 1 to pursue a limit of dPT 10-4.K